/*
 * Copyright (C) 2015 ScyllaDB
 *
 */

/*
 * This file is part of Scylla.
 *
 * Scylla is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Scylla is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Scylla.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include "bytes.hh"
#include "key.hh"
#include "core/temporary_buffer.hh"
#include "consumer.hh"
#include "sstables/types.hh"

// sstables::data_consume_row feeds the contents of a single row into a
// row_consumer object:
//
// * First, consume_row_start() is called, with some information about the
//   whole row: The row's key, timestamp, etc.
// * Next, consume_cell() is called once for every column.
// * Finally, consume_row_end() is called. A consumer written for a single
//   column will likely not want to do anything here.
//
// Important note: the row key, column name and column value, passed to the
// consume_* functions, are passed as a "bytes_view" object, which points to
// internal data held by the feeder. This internal data is only valid for the
// duration of the single consume function it was passed to. If the object
// wants to hold these strings longer, it must make a copy of the bytes_view's
// contents. [Note, in reality, because our implementation reads the whole
// row into one buffer, the byte_views remain valid until consume_row_end()
// is called.]
class row_consumer {
public:
    using proceed = data_consumer::proceed;

    // Consume the row's key and deletion_time. The latter determines if the
    // row is a tombstone, and if so, when it has been deleted.
    // Note that the key is in serialized form, and should be deserialized
    // (according to the schema) before use.
    // As explained above, the key object is only valid during this call, and
    // if the implementation wishes to save it, it must copy the *contents*.
    virtual proceed consume_row_start(sstables::key_view key, sstables::deletion_time deltime) = 0;

    // Consume one cell (column name and value). Both are serialized, and need
    // to be deserialized according to the schema.
    // When a cell is set with an expiration time, "ttl" is the time to live
    // (in seconds) originally set for this cell, and "expiration" is the
    // absolute time (in seconds since the UNIX epoch) when this cell will
    // expire. Typical cells, not set to expire, will get expiration = 0.
    virtual proceed consume_cell(bytes_view col_name, bytes_view value,
            int64_t timestamp,
            int32_t ttl, int32_t expiration) = 0;

    // Consume one counter cell. Column name and value are serialized, and need
    // to be deserialized according to the schema.
    virtual proceed consume_counter_cell(bytes_view col_name, bytes_view value,
            int64_t timestamp) = 0;

    // Consume a deleted cell (i.e., a cell tombstone).
    virtual proceed consume_deleted_cell(bytes_view col_name, sstables::deletion_time deltime) = 0;

    // Consume one range tombstone.
    virtual proceed consume_range_tombstone(
            bytes_view start_col, bytes_view end_col,
            sstables::deletion_time deltime) = 0;

    // Called at the end of the row, after all cells.
    // Returns a flag saying whether the sstable consumer should stop now, or
    // proceed consuming more data.
    virtual proceed consume_row_end() = 0;

    // Called when the reader is fast forwarded to given element.
    virtual void reset(sstables::indexable_element) = 0;

    // Under which priority class to place I/O coming from this consumer
    virtual const io_priority_class& io_priority() = 0;

    virtual ~row_consumer() { }
};